Amphistemon

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Asterids
Cladus: Lamiids
Ordo: Gentianales

Familia: Rubiaceae
Subfamilia: Rubioideae
Tribus: Spermacoceae
Genus: Amphistemon
Species: A. humbertii – A. rakotonasolianus
Name

Amphistemon Groeninckx, Bot. J. Linn. Soc. 163: 450. (2010)

Type species: Amphistemon humbertii Groeninckx, Bot. J. Linn. Soc. 163: 450. (2010)

References

Groeninckx, I., De Block, P., Robbrecht, E., Smets, E.E. & Dessein, S. 2010. Amphistemon and Thamnoldenlandia, two new genera of Rubiaceae (Spermacoceae) endemic to Madagascar. Botanical Journal of the Linnean Society 163(4): 447-472. DOI: 10.1111/j.1095-8339.2010.01060.x Reference page.
Govaerts, R. et al. 2019. Amphistemon in World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the internet. Accessed: 2019 Jan. 1. Reference page.
International Plant Names Index. 2019. Amphistemon. Published online. Accessed: Jan. 1 2019.
Tropicos.org: Catalogue of the Vascular Plants of Madagascar: Amphistemon. Missouri Botanical Garden. Published on the internet. Accessed: 2019 Jan. 1.

Amphistemon is a genus of 2 species of flowering plants in the family Rubiaceae. It is described by Inge Groeninckx in 2010 based on a molecular analysis of the Hedyotis-Oldenlandia group.[1] The genus name is based on the Greek 'amphi-' (=double or of two kinds) and 'stemon' (=stamen) referring to the dimorphic stamen position characteristic for this genus.

Description

Amphistemon are erect perennial herbs or subshrubs with the unique feature in the Hedyotis-Oldenlandia group of having stamens inserted at two distinct levels in the corolla tube, the lower stamens with filaments and anthers shorter than those of the upper stamens.[1]
Distribution and habitat

It is endemic to southwestern and western Madagascar and is found in dry spiny forest-thicket and coastal bushland.[1]
Taxonomy

According to molecular analysis of the genus, it is found to be closely related to Astiella of the species-group Hedyotis-Oldenlandia.[1]
Species

Amphistemon humbertii Groeninckx
Amphistemon rakotonasolianus Groeninckx

References

Groeninckx I, De Block P, Robbrecht E, Smets E, Dessein S. 2010. "Amphistemon and Thamnoldenlandia, two new genera of Rubiaceae (Spermacoceae) endemic to Madagascar." Botanical Journal of the Linnean Society 163: 447-472.